Researchers Finally Confirm that Marijuana DOES NOT Lower IQ in Adolescents

Written by on June 7, 2019 in Sci-Tech, Science with 37 Comments

Video Source: Buzz60

By Vandita | We Are Anonymous

Is marijuana linked to cognitive deficits? No. Is marijuana the ‘gateway drug’? No. Can smoking marijuana damage the lungs? No. Does marijuana cause anxiety and depression? No. Is adolescent marijuana use associated with IQ or educational performances? No. Does marijuana kill cancer cells? Yes. Is marijuana legal? No. Wonder why? Because Big Pharma doesn’t want it.

In October 2012, a study, more than thirty years in the making found that smoking marijuana permanently lowers intelligence quotient or IQ. Persistent marijuana use, the researchers found, was associated with neuropsychological decline broadly across domains of functioning. Further, the researchers claimed cessation of marijuana use did not fully restore neuropsychological functioning among adolescent-onset cannabis users. In the end, the researchers concluded that marijuana has had a neurotoxic effect on adolescents’ brains.

Less than four years later, a pair of studies investigating how the IQ of adolescent marijuana users compares to that of their abstinent peers found that no measurable link between marijuana use and lower IQ existed. The first study (conducted by researchers from University College London, Queen Mary University of London, and University of Bristol) observed:

“There is much debate about the impact of adolescent cannabis use on intellectual and educational outcomes. We investigated associations between adolescent cannabis use and IQ and educational attainment in a sample of 2235 teenagers from the Avon Longitudinal Study of Parents and Children… Those who had used cannabis ⩾50 times did not differ from never-users on either IQ or educational performance.

“These findings suggest that adolescent cannabis use is not associated with IQ or educational performance once the adjustment is made for potential confounds, in particular, adolescent cigarette use. Modest cannabis use in teenagers may have a less cognitive impact than epidemiological surveys of older cohorts have previously suggested.”

So what caused lower IQ levels among those who had smoked marijuana at least 50 times by the age of 15? The researchers found that higher rates of childhood behavioral problems, depressive symptoms, and other substance use – particularly alcohol and cigarettes – discovered among marijuana smokers, may have been responsible for their reduced IQ. In fact, since marijuana users were 17 times more likely to also smoke cigarettes, the researchers speculate that cigarette use may be a more reliable predictor of reduced IQ in the study group.

In the second study (conducted by researchers from University of Southern California, University of Minnesota, University of Pennsylvania, and Orebro University), the effects of marijuana on the IQ of around 2,000 adolescent twins living in Los Angeles and Minnesota (where one twin was a regular user, while the other was not) were examined over a period of nearly a decade.

“Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change.

“Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.”

The two studies clearly indicate that marijuana is an unlikely cause of any IQ decline. The question raised, then, is why are we forced to believe that marijuana is linked to cognitive deficits, such as memory loss and low IQ? For the same reason why we were brainwashed for more than five decades into believing that saturated fat causes heart disease when the culprit was actually sugar. Big Pharma doesn’t want you to know the truth. Period.

This article (Researchers Finally Confirm that Marijuana DOES NOT Lower IQ in Adolescents) is a free and open source. You have permission to republish this article under a Creative Commons license with attribution to the author and

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  2.' Rachel Marie says:

    It does however affect their motivation in life to an extreme level.

    • I have smoked weed for 35 years, I am a mother of 2 sons, college graduate, home owner, business owner, competitive athlete, personal trainer, motivational speaker and so much more.. So if your claim is marijuana Is a Motivator You Are CORRECT!!!.. I Don’t smoke cigarettes or consume alcohol and I am currently enrolled in Open Courseware at MIT… I am up at 5:30am Monday – Saturday teaching yoga, meditation or running 5k with clients…

    •' Rachel Marie says:

      It depends on the person but when teens nowadays do it, they get real lazy.

    •' Anna Inaka says:

      I think teens are more lazy today than before due to a rapid changing society and things like advanced technology. Most kids now feel as though they are entitled to receive everything without working for it and are more selfish than ever before.
      The kids today believe they should be handed everything and dont need to work hard for things they want in life-whether they smoke weed or not. I do agree, some people can definitely be affected negative by marijuana (and any substance legal or not can be abused) but when you compare the plant against alcohol (which is responsible for countless deaths each year), you start to see why some people would prefer a weekend joint to a weekend of drunkness 🙂

    • Again… I Know many teens who smoke and are highly motivated, highly intelligent and highly productive human beings… So please stop insisting it is Most… It is Not… it is Few….

  3. That’s because stoners already have as low an IQ as it is possible to have

    • Really?? I have smoked weed for 35 years, I am a mother of 2 sons, college graduate, home owner, business owner, competitive athlete, personal trainer, motivational speaker and so much more.. I Don’t smoke cigarettes or consume alcohol and I am currently enrolled in Open Courseware at MIT… I am up at 5:30am Monday – Saturday teaching yoga, meditation or running 5k with clients… My IQ could run circles around your narrow minded opinion…

    •' Chris Miller says:

      And you were born with a naturally low iq … Troll

    • Boohoo…and they take themselves far too seriously

    •' Chris Miller says:

      You are a living tampon who obviously was deprived of love and oxygen as a child .. So Craig shut your lips dumbass

    • Thank you Chris Miller Spot On!#tampon I ??? it!!

    •' April Flower says:

      Actually,all the pot smokers I have met in my life were severely deprived of love from their parents,unloved by their mothers and abandoned by their fathers.
      All of them were also alcoholics,sex addicts,gamblers,liers or had some personality disorder and definitely anger issues.. marijuana is widely misused. I believe it has amazing healing properties when used properly.

    •' April Flower says:

      Craig,I would not necessarily agree they have low IQ,which btw is not the worst thing to have,but they do become the worst possible people to live with bc they lose all the empathy and they become emotionaly cruel toward others..or better said numb which in my opinion they stop being human..had too much experience with people like that..

    • April Flower, I am an intuitive empath, I have been working with people who live with PTSD, Traumatic Brain Injury and Autism for 15 years….My entire business practice revolves around kindness and compassion….sit down girl you may hurt yourself..

  4.' Chris Mate says:

    It lowers the use of it.

    • I’ve smoked weed for over 35 years and attended college on an academic scholarship.. and to think you have the ” golden ratio”as your profile picture… sit down son you might hurt yourself… Go back to school.. You need a lesson…

  5. Not true. …believe nothing, question everything

  6.' Chris Miller says:

    Whoever did these tests is an idiot .. That’s my thought

  7.' Bunny Brando says:

    IQ means nothing, no way to measure intelligence, don’t buy it, teach peace and love, everyone owns their genius, we al genius, respect one another

  8. whatever the lQ must adolescents smoke anything to make them high.

  9. Craig Marsden..I may be stupid..but al least I’m pretty…bitch. haha!

  10.' James Melchi says:

    This article is set to fail from the get go, does smoking weed damage your lungs, fucking yes, a few days after you stop smoking bongs your lungs try to excrete tar and shit by coughing shit Up, it’s not pretty

    •' Chris Miller says:

      Or drink alcohol , or shove McDonald’s down your throat or be a heroin addict .. Everyone has their vice in life .. So for you asshats living in your glass houses get your heads out of your asses build a bridge and get over yourselves .. We all do something to vent or relieve some type of pain or ailment whether it’s mental emotional or physical .. And if you think not your a damn liar.. Don’t bother responding negatively because I don’t confer with morons . Just know I have a bucket full of stones for your glass houses ..

    •' Alex Biddle says:

      try vaping Weed no tar build up just a nice clean high 😉

    •' Alex Biddle says:

      or even eat it when its been prepared properly still no tar build up only benefits to be had. Education is key in this area.

    • Smoking anything has never been a great thing to do. Vaping seems to be a logical alternative.

    • I’ve Been smoking weed for 35 years, I run 5k’s 3-5x’s PER WEEK!! I am a personal trainer and have completed 3 triathlons and 1/2 marathon and I teach Kundalini yoga …I haven’t had a cold or any sickness in over 12 years nor missed a day of work or working out…I breath just fine… you have no idea what you are talking about James Melchi…sit down son… you might hurt yourself…

    •' James Melchi says:

      Wow I shared my opinion and you go stupid, I realise you are omnipotence on earth but you can’t change what I’ve personally experienced so get off your high horse and get some humble into you by finding more constructive things to do aside from om discrediting me through your life experiences, you mean nothing to this world don’t forget it

  11.' Alex En says:

    Duong Cari always been clever ?

  12.' Adrian Kealy says:

    My lungs are perfect, after giving up cigarette tobacco to skin up with, just use the lightest papers & American spirit tobacco to roll with. I even really deteste cigarette smoke, the smell..everything. If weed wasn’t illegal, I wouldn’t have to smoke it, be cheap enough to eat it, which is way more healthy & no harm at all. The only times weed makes one lazy is if one smokes too much with too much drink on a really hot sunny day.. then yeah.. it’s like ‘chill out & do fuck all..’

  13.' Chris Miller says:

    You weed critics know nothing of the subject so save the stupid shit for someone who believes it like the other uniformed idiots

  14. I was a paramedic for many years seeing all kinds of problems associated with the many and varied drugs out there in society. The one thing I did notice, was that those who smoked cannibis were far more polite, friendly and well informed than people using any other kind of substance – especially moreso than those who routinely use alcohol. As well as this, I never attended an accident caused by a cannibis user – hundreds of alcoholics killed people and their families, but cannibis wasn’t a factor in any accidents I ever attended. So as far as I’m concerned, I’d prefer to associate with those who choose to smoke weed after work than those who drink or do synthetic drugs. You have a far more interesting and intellectual conversation ahead of you…….

  15. maybe not…but my grades went from A’s to D’s when i smoked in University them back to A’s when i stopped…from a 60 something who uses to alleviate the symptoms pf PTSD….:)

  16. Marijuana eventually makes you impotent.

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